10 bolt faq

[The Griff]

Quote: Originally Posted by zerogravity58

from what i remember off hand the only trucks that might of came with 4 wheel disk brakes are the xtremes. The rearend you have should has the 28 spline axles. if anything i would keep the rear you have and throw in a eaton or auburn posi. You can adapt the disk brakes from a 3rd or 4th gen camaro onto your rearend.

right on, thanks man, that would probobly save me a pretty penny

[zerogravity58]

The 8.8 is a good rearend. You wouldnt have to get it shortened either, you could just buy new back wheels but either way its going to cost a few hundred bucks plus the cost of the rear. A gm rearend is not that hard to rebuild. All you would need is a good posi, shims, support cover, and if you deciede to change gears buy the gears and the solid spacer. The only tool that you really would need is something to check the backlash with. Other then that its pretty much straight forward. Jack truck up take off wheels, pull diff cover, check backlash, take out set screw from carrier(holds the pin in), remove pin, slide out axles, remove carrier(2 bolts on each cap, 4 total) If your going to use the same gears thats as far as you need to go. Put the ring gear on the new carrier, slide carrier in and check backlash. Try to get the backlash the same as it was before you pulled the old carrier out. Might take a few times of trying diffrent shims to get it right. When you put the carrier in with the shims tightened up the caps so you can get an accurate reading. Then if you need to increase the backlash add spacers to the left side, decrease backlash add spacers to the right side. Slide axels back in, install c clips, put pin in carrier and set screw, Install the supports cover and torque the bolts to 15lbs if i remember right, add gear oil, put wheels back on and test drive. When i built my 7.5 10 bolt i bought a auburn posi off ebay for around $120. A shim kit will run you around $20-30. plus a few quarts of gear oil. I built mine with a auburn posi, 4.11's, and support cover(no solid spacer) and ran that for a year, then i sold it and someone else ran it for a few years before the posi finally took a crap.

[litemup]

To make a long story short just tell me if I can and what to get to put in my 88 s-10 rear to make it full posi or locker with 4:88 gears for racing and will it hold up to 4 to 500 horse or should i go to a ford nine inch.

[zerogravity58]

If your going to be racing and using a decently big tire or slick dont bother with the 7.5 because if wont last. It may last for a year or so but it wont be reliable no matter what you do to it. Id put the 9" or better yet bolt in a 8.8 out of a explorer. Will bolt right in just need diffrent wheels and backspacing.

[King_Ice_Flash2]

With the solid pinion spacer, what does the nut get torqued to?

[litemup]

Quote: Originally Posted by zerogravity58

If your going to be racing and using a decently big tire or slick dont bother with the 7.5 because if wont last. It may last for a year or so but it wont be reliable no matter what you do to it. Id put the 9" or better yet bolt in a 8.8 out of a explorer. Will bolt right in just need diffrent wheels and backspacing.

Thanks a bunch. This will be strictly racing. wILL start looking around for some ford rims.

[zerogravity58]

i honestly dont remember the torque specs on the pinion nut but im sure any S10 manual will tell you

[King_Ice_Flash2]

Quote: Originally Posted by zerogravity58

i honestly dont remember the torque specs on the pinion nut but im sure any S10 manual will tell you

I have the factory specs, but I wasn't sure if it changed with the solid spacer instead of the crush sleeve.

[Johnnyby68]

i have a curious question. i wanna do a rear swap or build the rear i have. i have an 82 s10, orignally had a 1.9 japanese 4 cylinder, with a 4 speed manual.

my plans are to build the motor thats in it (350 chevy) to about 400 hp or so. also swap the th350 for an st-10 4 speed manual. and possibly drag race it at the strip a few times. maybe with slicks i'm not sure.

now i think i have a 4x4 rear in my truck, reason for thinking that is i have 8 inch rims all the way around and the back wheels stick out about 2 inches past the fenders. all the wheels have the same offset.

now should i get a 2wd drive 7.5, rebuild that with a posi and 3.42's. or get an 8.5 and just be done with it. thanks in advance for the input

[gmax111]

8.5 if you can find one... but most likely it wouldn't be posi or limited slip

[zerogravity58]

id look for the 8.5, I run the 8.5 with a full spool, 4.56's, c clip eliminators, support cover, and factory 30 spline axles for now. I went 10.7's on it so far and faster this year.

[BuickGSXJuiced]

Quote: Originally Posted by zerogravity58

Before you can adjust pinion dept you must set backlash. The best way to obtain backlash reading is with a dial indicator. You should be able to get a close indication of initial pinion depth if the backlash is within, or very close to the .006” - .010” specification. On most ring and pinion sets backlash will change about 0.007” for each 0.010” that the carrier is moved. Therefore if you need to decrease the backlash by 0.007”, move the carrier 0.010” closer to the pinion by shimming the left side. If you need to increase the backlash by 0.007”, move the carrier 0.010” farther away from the pinion by shimming the right side. Use a pencil and paper to keep notes of shim combinations and backlash. A calculator might also come in handy.

After setting the backlash you can check pinion depth. Do this by brushing three or four of the ring gear teeth with a moderate coat of compound in two locations on the ring gear. Rotate the ring gear past the pinion gear four or five times to print a good pattern. The gear marking compound will show a clear pattern of pinion contact on the ring.

The pattern you’re looking to achieve should be oval in shape and centered between the face and flank on the drive and coast side of the ring gear teeth. There should be an area of no contact below the face and above the heel on both sides. It would be ideal if the pattern was also centered between the heel and toe of the ring gear, but that is not necessary. The only part of the pattern that helps set the pinion depth correctly is the contact position between the face and flank of the teeth, regardless of the location concerning heel and toe. I’ll say it again; if the contact pattern is towards the heel or the toe of the ring gear teeth ignore that and look only at the position from face to flank. In most cases an ideal heel to toe pattern can not be achieved anyway. Trying to make adjustments to get a pattern that is centered from heel to toe will usually lead to frustration and a noisy gear set. The position of the pinion bearing bore in the housing and housing alignment affects the pattern from heel to toe and can not be corrected without machine work. So once again, a contact pattern that is centered from face to flank on the drive and coast side always indicates correct pinion depth even if the pattern can’t be centered from heel to toe.

If the contact pattern is towards the face of the ring gear teeth then the pinion is too far away from the ring gear. To correct it the pinion needs to be moved towards the ring gear with a thicker shim to position it closer to the ring gear centerline. If the contact pattern is towards the flank of the ring gear teeth then the pinion is too close to the ring gear. To correct it the pinion needs to be moved away from the ring gear centerline with a thinner shim. The shim is located between the gear and rear bearing.

If the backlash is within spec but the pinion depth is not correct you match-mark the driveshaft to the pinion flange and remove the driveshaft and suspend it with wire out of the way on something like the exhaust pipe. Match-mark the pinion flange, pinion shaft and nut (if you’re reusing the nut). Now check the bearing pre-load using an inch-pound torque wrench and record it before disassembly. The pre-load is the torque required to just begin turning the pinion shaft.

To remove the pinion nut and washer you will need to use a special flange holding tool or breaker bar to hold the flange in place while you loosen the nut. You may also want to install the cover loosely with a couple bolts so the pinion doesn't fall out. With the nut and washer off use a two-jaw puller to withdraw the flange by placing the two jaws on the backside of the flange and the puller screw on the pinion. Examine the sealing surfaces of the flange for nicks or gouges. Replace the flange if it's damaged. Use a blunt chisel to remove the pinion oil seal, being careful not to damage the carrier housing. The pinion can now be removed from inside the carrier case to replace the bearings, races, correct thickness shim and crush sleeve. It’s easiest to assemble the pinion without a crush sleeve until the correct pinion depth has been established. Install the new pinion oil seal. When initially installing the pinion slowly tighten the pinion nut until the pre-load is within the assembly specifications of 12-15 in. lbs. on a new pinion gear and 6-7 in. lbs. on a used pinion.

Understand this is the hard way to set pinion depth without the six or seven special jigs, and guage a GM tech has available. They can simple install the various jigs and get a reading on the guage that translates into the correct thickness shim required.
When changing the pinion depth always make large changes until the pattern is close. Consider 0.005” to 0.015” to be a large change and 0.002” to 0.004” to be a small change. Changes of 0.005” to 0.008” or more will lead to the correct pattern faster than small changes will. If you move the pinion too far and the pattern changes from one extreme to the other then you know that the correct pattern is somewhere between the two extremes. Once you get close to the correct pinion depth make smaller changes until the pattern is centered between the face and the flank of the ring gear teeth. After the backlash and pinion depth are set remove the carrier and set the final pinion bearing pre-load of 12-15 in. lbs. on new pinion gear and 6-7 in. lbs. on a used pinion. Use a new crush sleeve for final assembly. Use oil on the pinion nut washer surface during all assemblies and red Loctite on the pinion nut threads during the final assembly. The oil on the washer surface helps the nut turn easier while it is being tightened and the red Loctite helps keep it tight.

On a crush sleeve design differential it usually takes between 300 and 400 foot pounds of torque to crush the crush sleeve. Use a large breaker bar and or very strong air operated impact wrenches to crush the crush sleeve. Proceed very slowly so that you get it right the first time. The pinion preload will be zero until the bearings contact the races. When the bearings contact the races the preload will increase very quickly. Take plenty of time to set the preload carefully so that the bearings will have a long life. If the crush sleeve is over crushed and the pinion bearing preload exceeds the specified allowable range the only solution that I know of is to install another new crush sleeve and start over. After reaching the correct pre-load, moderately tap both ends of the pinion to seat the bearings, races and yoke. Be careful not to hit the pinion so hard that it damages the bearings. After “seating” the pinion check the pre-load again to make certain that it is correct.

After setting the pinion depth, backlash, and pinion bearing pre-load it’s time to set the carrier bearing pre-load. During the original set-up you set the backlash with very little carrier bearing pre-load. Now set correct pre-load by inserting equal thickness shims to each side. Make it fairly tight, as tight as you can without damaging the shims while driving them in. If the pre-load is close and the backlash is wide, add shims to the left side. This increases the carrier bearing pre-load and decreases the backlash at the same time. If the pre-load is close and the backlash is too tight, add shims to the right side. This increases both the carrier bearing pre-oad and the backlash at the same time.

Now that the pinion depth, pinion bearing preload, backlash, and carrier bearing preload are set recheck the pattern once more to be certain that everything is perfect before final assembly.

All new gear sets require a break-in period to prevent damage from overheating. After driving the first 15 or 20 miles it is best to let the differential cool before proceeding. 500 miles are recommended before towing. Tow for very short distances (less than 15 miles) and letting the differential cool before continuing during the first 45 towing miles. This may seem unnecessary but many differentials are damaged from being loaded before the gear set was broken-in. It's also recommended to change the gear oil after the first 500 miles. This will remove any metal particles or phosphorus coating that has come from the new gear set.

I don't understand how your getting these measurements without unpressing and repressing the pinion bearing, because the shims are between the pinion gear and bearing?

so say I'm going to put 3.73's in my truck that has 3.08's, both gear sets are GM. so why can't I just put the same amount of shims from the 3.08's pinion to the 3.73's pinion??? and with the posi I bought for this upgrade too, just shim that to mess right with the pinion???

[bigkuntryboy27]

Hey, I Need A Little Help. I'm A Broke Guy Tring To Get My Gears Replaced That I Knocked A Few Teeth Off Of. What Do I Really Need To Replace? Just The Ring & Pinion, Or That Plus All The Bearings And Everything? Im Really Not Sure And Im Broke So Cheaper Is Better For Me. Thanks

[zerogravity58]

you can just replace the ring and pinion. If you buy a used ring and pinion you wont have to reshim the pinion just the carrier. All you would need is new carrier shims and a new crush sleeve and you would be good. You can find a set of gears in a junkyard for probally $75

[SlowAndLo]

auburn with 4.10 gears with posi pulled from a 96 camaro, would this benefit a stock s10 with a 7.5 rearend at all, and how difficult would the swap be?

[bloaty57]

Guys,

I thought you all might benefit from this link;

http://www.sethirdgen.org/10bolt1.htm

I've done several GM rears, and chopped a few Ford 9's for streetrods. Many times with the S10's the axle length is a big detractor with swaps. 8.5's can be cut (as any), but the inner tube ends have to be cut due to the outer end of the tube being tapered. Grinding the tube welds from the housing to pull them takes a little work.

Many times, for the amount of work & money it takes, it's cheaper ( in the long run) to buy the housing and axles from Moser, or from;

http://www.currieenterprises.com/ces...t_9track9.aspx

....and specifically this link........http://www.currieenterprises.com/ces...694&p=964.9500

Zero Gravity is right about the housings......they're the weak link in the 7.5's. Many guys use the 7.5's that come in the S10 chassis when they do the frame off builds regarding streetrods. They're just using them for cruising, and a short pounding once in awhile. They hold up fine for that.

I have seen a couple come apart on burnouts, but 99% of the time, it's due to a sticky startup, and too much too quick I guess.

I don't use anything less than the 8.5's, and the Ford 8.8's and 9's are pretty easy to get ahold of. I like the GM 10's and 12's a lot, and they're relatively easy to build if you take your time and pay attention to detail.
On the C-clip eliminators, Moser will tell you that they aren't recommended for regular street use. I opted to buy a set and try them out on a GM 12 bolt that I had built and was going to install in a buddy's blown 69' pickup. Luckily I called and talked to the techie's before I bought the kit.

Maybe they changed them since, but I don't think so.

I'm kinda anal about using Ford pieces on Chevy's....call it "old school weirdisms", , or the old Ford v. Chevy thing from the old days, but they do make a well designed rear. The lower pinion center on them is their only weak link, and there are notes regarding the pinion covers, and which ones to use.

http://www.ultrastang.com/Rearinfo.asp?Page_ID=1

Some ID photos (same as S10) and other info for possible swaps;

http://www.novaresource.org/axle.htm

http://www.2quicknovas.com/happyrearends.html

The GM 10 bolts have remained relatively the same since their inception, so the rebuild info should be the same. Moser and Mark Williams (http://www.markwilliams.com/ ) both sell shortened replacement and/or high performance axles for a housing chop. Many times, if the job is a little nervy for some, they'll chop the housing and fit the axles for you, just to make sure. I sent two axles to Moser to be cut & fit for axles several years ago, and they did a nice job. I think it cost me about $400, including the axles....not bad.

Well, enough rambling.........

Good luck, hope this helps,
Bob

[juicedxtreme]

my rear end is getting rebuilt this week, richmond 3.73's, auburn posi, all new bearings and everything else, is there something i need to do to break it in??

[bloaty57]

juiced,

A good quality gear oil per spec, or better, and drive it.....
....but don't hammer on it for a couple of hundred miles. Just normal driving. Your trying to marry two machined surfaces, or blend them with each other.

I'll usually run the vehicle to the closest 2 lane highway and run it at varying speeds from 40 to 65 or so to break things in, and to listen for possible signs of a problem. Usually I'm good to go. Then I'll drive it for an hour or two, just going along steady.

Personally, I change out the gear oil after the first 1000 miles, and replace it .

Royal Purple is good stuff by the way......

Check your posi unit as some of them require specific additives...........


Bob

[juicedxtreme]

thanks for the advice im gonna do that!

[SlammedWhitey03]

Alright on the 98+ 2WD Blazer rears, I'm under the assumption there are 2 different ones. The 7.5" and the 8.5" version, right? I called the local salvage yard and they said they have both of them on the yard. So what is the easiest way to tell them apart at first glance? I'm wanting something stock length (90 model S-10 2WD) and the 12 bolt from the Nova isn't cutting it. And while I'm asking questions, what length should the rear measure so I know I'm good to go when I pick it up Friday?

Chris
Acro Texas

[zerogravity58]

the 7.5 cover is more square while the 8.5 cover is perfectly round. Also another way to tell is 8.5's have tappered axles tubes where the 7.5's are the same size all the way down. S10 did come with 8.5's and 7.5's after 98. 8.5 came in both 2wd's and 4wd's. The 4wd rears are always 4" wider then then 2wd rears. They are interchangable so you could but a 4wd rear in a 2wd and vise versa but you would have to change wheels.

[SlammedWhitey03]

So what is a roundabout estimate on the length of the 2wd rear? Somewhere around 52-54""? I had a 10 bolt from a Blazer for my old truck that was SUPPOSED to be 2wd and when I put it under the truck to see if it was going to work it appeared to be too long. I think it measured 58", so I sold it and forgot all about doing the swap.

Thanks for your help,
Chris

[bloaty57]

zero & whitey,

I'm not totally sure about the 98' rears, but the 7.5's had the rounded looking ears on the corner's, and the 8.5's had the squared ears.

Zero was also right about the diff. cover's shape, and tapered tube ends where the backing plates are. If you get the 8.5 rear out of a 98', you can use the disc brake setup off of the later model ZR2 Blazers and it'll bolt right on.

The ZR's had the same 8.5 rear, but it was longer, like the Nova's. I grabbed a Nova posi from a 73' axle, and if I can get my hands on a 98' S10 8.5" rear, then I'll build a posi unit with the disc brakes, like I mentioned.

My 91' chassis has the stock axle under it now, and I'd like to keep the axle length that it has, rather than stuff the Nova rear under it, which is a little longer than I want. All 8.5 components will interchange as long as you have the same spline count on the axles.

Take care,
Bob

[gijoeoif3&5]

Hello I have a 2000 s10 2.2l auto trans ext cab. I beleave I have the 7.625 I'm in iraq right now so I cant just pop under and check you see. I'm about to be running some 22" rims, but ever since I put my 20's on. I lost alot of my off the line pick up. So I dont even wont to know how bad it will be with 22's. So I'm looking into changing my gears out to compesate. What do you think would be a good number 3.73,4.10 ect. to run. Now I'm not trying to race or nothing. I just hate having to wait an hour to go from 0-60. I also wont to run an Auburn or Eaton posi setup so I would like something that would work nicely with it.If anyone has a recomendation it would be a great help thanks.

[SlammedWhitey03]

The truck currently has a Nova 12 bolt under it with 3.73's and a Detroit locker. If I end up with the 8.5" from the Blazer is there any way the locker and gears would work, or would I need to start over?

Chris
Acro Texas

[bloaty57]

gijoe,

With the 2.2 four banger, and the 4L60E tranny, I think GM was very fond of putting 3:73's in the rear as a standard gear. With the 20" rims, in comparison to the stock rims & tires, it's the overall diameter difference that affects it all.
In other words, if your old rim & tire combo was, lets say 24" overall, and even though you changed to 20's, with the tire, the outside diameter stayed the same, there literally should be no difference.

If you increase the overall diameter, you will have a difference, but it shouldn't be too overly noticable. It's possible that your hooking up more due to the fatter, flatter, and shorter sidewalls of the tires that go on the 20's. Being that your running a smaller motor, and maybe hooking up tighter, it's giving you that doggie feeling.

You can run 4:11's along with that engine & tranny, and with the overdrive, still get fairly decent gas mileage, but it won't be near what your getting now. The pickup will be far quicker though.

I used 4:11's recently in a rear I built with a friend of mine because he was using a T56 6 speed tranny (standard) , that has both a 5th and 6th speed overdrive. The 5th gear was a standard 1:1 ratio, and the 6th gear was a .6 ratio.

Great mileage in the top gears, and snotty street performance in the lower ones........best of both worlds.



Whitey,

Since the outer dimensions are all the same, measure your backing plate to backing plate length (which I think is 48"). This will give you a quick reference of "use-ability". Look at the "pumpkin" and it should be not only round like Zero mentioned, but you should have two "squared" ears on the two bottom corners of the pumpkin casting.

If they are "hooked" looking, or like someone drilled a big hole in the ears, and ground off the bottom edge of it, then it's a 7.5.

The link below shows photo's of the rears were talking about, and their individual identifying characteristics.

http://www.novaresource.org/axle.htm

The junkyard boys "should know" the differences between them, but several times, I've been surprised when directed to a supposed axle that was suppose to be something it was not.

Also like Zero mentioned, the outer ends of the axle tubes should taper down out where the backing plates bolt on.

If you find the one your looking for, and it's the same size as the one that's in your truck now (width wise), let me know what it's out of. I'm looking for another housing to fit my project, and it needs to be "that" same size (stock S10). The Nova 8.5 I have right now is a little too long.

Take care,
Bob

[bloaty57]

Double post..........deleted

[zerogravity58]

hey bloaty dont forget your nova posi wont work with a S10 8.5 10 bolt. Nova's came with 28 spline axles and all 8.5's from S10s have 30 spline axles

[bloaty57]

Yeah I considered that, but I wasn't sure if any 8.5's came with 28 splined units without checking the later model carriers. Sh*t.........

One reason why I figured I'd just get the whole 8.5 S10 rear if I could figure which year they became available. Moser will send me a set of 28 splined axles to fit the S10 axle housing if I decide to use the stock Nova posi center I have now, but I can get as much for the whole rebuilt rear as it would cost me for a new Eaton or Auburn posi.

I can always use the 8.5 housings, and I grab them when I can, but the standard S10 axle width in that size would be worth more for streetrod use.

Anyway, I'd rather run with the 31 splined units if I can. The 28's will hold up fine for what I do, but mixing and matching can be depressing sometimes.......

Thanks,
Bob

[bloaty57]

Zero,

BTW- I meant 30 spline....I guess I've got Ford 9's on my brain lately.


For some duma$$ reason, I guess I kept thinking I had 30 splined axles in that Nova rear.....you're right, I think they all were 28's.

I did consider the spline count back awhile ago, but I apparently was under that ASSumption............................I stand corrected.

I know that they had 8.5's in the ZR's, which were longer, but I wasn't aware of the 8.5's being used in the standard S10's......must be relatively recent.

What years, do you know ?

TKS,
Bob

[Jetmeck]

Good info...kudos to the thread starters. As stated a 7.5 will not hold up to slicks and quarter mile runs for long term.

This has been COMMON knowledge to Third gen Firebird/Camaro crowd for years. A nicely built 7.5/7.625 will up to 350-400 hp without slicks over the long term.

For a stock to mild bolt on S-10 they are more than adequate. Anyone breaking one of these on a stock v-6 is driving like an idiot or had a bad one period. I got flamed relentlessly months for stating the same as this thread has. F all you haters. You know different now.

[bloaty57]

The stock 7.5 S10 rear will hold up to considerable pounding for what it is.
Under normal cruising, and the occasional hammering now & then, it'll do just fine.

It's the sudden launches with grippy tires, as you mentioned, that causes them to come unglued. Normally, they hold up to 350HP pretty well. Most stock smallblocks don't clear 300 very often.

If you're going beyond 400HP, you either need a relatively light foot, or a heavier rear.

Bob

[zerogravity58]

8.5's cam behind the 4.3's with 5 speeds from(i think) 99 and up 4.3's. Not all 5 speeds had the 8.5 tho. I know i went a few 11.2's on a MT streets with my 7.5. Then i broke both axles and shattered the ring gear so i upgraded to a 8.5 and never broke in running 10.5's cutting a 1.5 60's

[bloaty57]

Zero......

I hope you're right.........at least close.....

Instead of building one (old Nova), I'll see if I can pick one up in the local boneyard.
For what it cost to build the one, I can probably pick up an 8.5 S10, and install a posi unit in it.

I can get the rear for $100-$200 depending on how good a mood my buddy's in that day. If I can find another late model (30 spline) 8.5, with a posi, I can grab both and mix & match.

Pondering.............

Bob

[Kurt]

So going from 7.5 to 8.5 how much do you have to shorten your driveshaft?

I seen a pic before of the lenght difference between them, but can not find that pic now.

[Kurt]

Quote: Originally Posted by Kurt

So going from 7.5 to 8.5 how much do you have to shorten your driveshaft?

I seen a pic before of the lenght difference between them, but can not find that pic now.

Ahh, this was the thread I was thinking of... http://www.blazinlow.com/forum/showthread.php?t=42856

No specfics on the DS shortening though.

[zerogravity58]

i dont think you have to shorten the driveshaft. I can remember. When i swamped mine in a had a new driveshaft made so i never checked to see.

[blazinred87]

Awesome thread. Very informative.



Anyways, here's my question. I read that a 7.5 can take a good amount of beating with street tires. I have an 87 S10, not converted to V8 yet, but that's not what I'm asking about.


I have an S10 rearend installed in my 75 Vega. A very light car, 2700lbs to be exact, most of the weight up front with the engine. If I do all that you say, Auburn diff, weld up axle tubes, get rid of crush seal and so forth, do you think it's possibly to run the ET Streets that I have like once a month at the strip? It's a street/strip car. Also, can I reuse the 3.70 gears on used posi unit I might buy off ebay sometime in the near future? How does the Auburn diff compare to say a later S10 unit like this one?
http://cgi.ebay.com/ebaymotors/GM-Po...em180154313706
I will count the splines once I go outside in a few minutes, I hope it's 28.


Thanks in advance.

[mij]

if you were going to buy a auburn carrier would i be that much beter off to go with the 8.5"? Id have to get a 8.5 carrier , rear end, gear,and sounds like shorten my drive shaft.If i stuck with the 7.5 i have i just buy the carrier , install kit and im done.I even reuse my gear.I only have around 300 hp at the motor.
Thanks
Jim

[zerogravity58]

if you just plan on having something to beat on on the street then id stick with with 7.5 and put a good carrier and a support cover on it. If yougo the 8.5 route its going to cost you roughly $700 for the rear, $300 for a carrier, etc you will have over 1000 in it where you can build the 7.5 for $500. probally cheaper if you shop ebay.

[gusdaman]

Thanks for all the info guys- but i have a question- I'm in the process of changing to 4.10s from 3.73s and installin a locker- I bought some gears and a carrier on ebay - which are 7.5" and 28 spline from a 1995 s-10. My question is, why does powertrax make a separate locker for 7.5" and 7.625" rear ends? On their application chart- http://www.powertrax.com/chevytrucklr.pdf
the 7.5 says 26 spline and the 7.625 says 28 spline- is it just assumed that 7.5" are 26 spline?
Lastly- are the 7.625 28spline and 7.5 28 spline carriers the same??
Thanks
GUS

[zerogravity58]

Quote: Originally Posted by gusdaman

Thanks for all the info guys- but i have a question- I'm in the process of changing to 4.10s from 3.73s and installin a locker- I bought some gears and a carrier on ebay - which are 7.5" and 28 spline from a 1995 s-10. My question is, why does powertrax make a separate locker for 7.5" and 7.625" rear ends? On their application chart- http://www.powertrax.com/chevytrucklr.pdf
the 7.5 says 26 spline and the 7.625 says 28 spline- is it just assumed that 7.5" are 26 spline?
Lastly- are the 7.625 28spline and 7.5 28 spline carriers the same??
Thanks
GUS

The 7.5 and 7.625 are the same and all of the parts are interchangable. All 7.5/7.625's starting coming with 28 spline axles around 88-89. Any 7.5's older then that came with 26 spline axles. But all the gears are the same and intershangeable along with covers, bearings, etc.

[bloaty57]

Kurt,

I know the differential necks are different lengths, but the only 8.5 I have here now to measure is the 73 Nova, and I'm not sure it'll measure the same as the 8.5 S10, or I'd cha-cha out to the shop and do it for you.

Zero,

Those later model S10 8.5's are a tough find. I've had 2 local yards looking for the last month and a half....nothing yet. Several S10's have come through, but no 8.5's on them yet.


Bob

[zerogravity58]

They are pretty tough to find. They only came in certain some s10 with the 4.3 and 5 speed. It took me awhile to find mine also. If i remember right You can use the same driveshafts between the two rears. The yokes and all are the same. search ebay also, i know they always have some on there but they are going for $800-900

[Kurt]

So, after alot of debating, I think the 8.5 would much less of a headache and still be decently strong. So when I find one, obviously I'll upgrade to a better diff unit and to a gear ratio better suited to my needs, but what else should I "beef-up"? I'm hoping to be in the neighborhood of 450ft/lbs through a T56, and should be dead hooking with some drag radials and "Boosted Thrills" built traction bars.

[Kurt]

Did I kill this thread?

[King_Ice_Flash2]

With that much power, you should consider a 8.8 or a 9" ford rear end. The 8.5 isn't that much tougher than the 7.5.

[zerogravity58]

I beg to differ. i ran my 8.5 for 3 years. Running 12" slicks on it cutting low 1.5 60's. Never had any problems with it. The 8.5 is almost just as strong as a 12 bolt. a 12 bolt is a 8.875 ring gear if i remember correctly. Grand nationals go 9's on the stock 8.5 10 bolts.

[King_Ice_Flash2]

I can not say I disagree. I was just saying that because I have seen a lot of used built 8.8/9 rear ends for sale that are already narrowed for wide slicks. I don't think I have ever seen a built 8.5 for sale. The only advantage I saw with the 8.5 was that it has a whole lot more aftermarket parts available to build it tougher than the 7.5, but if you are going to put money into it for axles, gears, covers, c-clip eliminators, you should probably consider other options too. The only real advantage is it bolts right into the truck.

The Syclone guy I saw up here was running in the 10's on the 7.5"

[Kurt]

Well, I checked on some G-Body sites and seems like most of those guys just upgrade the posi and call it good. Stock axles hold up, and they push their 8.5s alot harder than I will mine and they seem fine.

I have been watching for months and I have yet to find a used build 8.8/9 rear end that will bolt right in my truck. And chances are, if I do find one, it won't be the correct width.